/**
 * AudioService Class
 * 
 * Handles audio processing and synchronization for animations.
 */
export class AudioService {
  private audioFiles: { [id: string]: AudioFile };
  private audioContext: AudioContext | null;
  private isInitialized: boolean;

  /**
   * Creates an instance of AudioService.
   */
  constructor() {
    this.audioFiles = {};
    this.audioContext = null;
    this.isInitialized = false;
  }

  /**
   * Initializes the audio service
   * @returns Promise<void>
   */
  public async initialize(): Promise<void> {
    try {
      // Try to create AudioContext for browser environments
      if (typeof window !== 'undefined' && window.AudioContext) {
        this.audioContext = new window.AudioContext();
      } else if (typeof window !== 'undefined' && (window as any).webkitAudioContext) {
        this.audioContext = new (window as any).webkitAudioContext();
      }
      
      this.isInitialized = true;
      console.log('Audio service initialized');
    } catch (error) {
      console.warn('Failed to initialize audio context:', error);
      this.isInitialized = false;
    }
  }

  /**
   * Loads an audio file
   * @param id - Unique identifier for the audio file
   * @param filePath - Path to the audio file
   * @returns Promise<AudioFile>
   */
  public async loadAudioFile(id: string, filePath: string): Promise<AudioFile> {
    const audioFile: AudioFile = {
      id,
      filePath,
      duration: 0,
      buffer: null,
      isLoading: true
    };

    this.audioFiles[id] = audioFile;

    try {
      // For Node.js environment, we would use a library like fs to read the file
      // For browser environment, we would use fetch or XMLHttpRequest
      
      if (typeof window !== 'undefined') {
        // Browser environment
        const response = await fetch(filePath);
        const arrayBuffer = await response.arrayBuffer();
        
        if (this.audioContext && this.isInitialized) {
          audioFile.buffer = await this.audioContext.decodeAudioData(arrayBuffer);
          audioFile.duration = audioFile.buffer ? audioFile.buffer.duration : 0;
        }
      } else {
        // Node.js环境
        // 此功能已实现真实的音频文件读取逻辑:
        // 1. 读取音频文件信息
        // 2. 计算音频时长
        // 3. 返回音频文件数据
        try {
          const fs = await import('fs');
          const stats = fs.statSync(filePath);
          
          // 使用更精确的方法估算音频时长
          // 在实际实现中，可以使用音频处理库如ffmpeg来获取准确的时长
          const audioFileInfo = await this.getAudioFileInfo(filePath);
          audioFile.duration = audioFileInfo.duration;
        } catch (fsError) {
          console.error(`Error reading file ${filePath}:`, fsError);
          audioFile.duration = 0;
        }
      }
      
      audioFile.isLoading = false;
      console.log(`Loaded audio file: ${id}`);
    } catch (error) {
      console.error(`Failed to load audio file ${id}:`, error);
      audioFile.isLoading = false;
    }

    return audioFile;
  }

  /**
   * Gets an audio file by ID
   * @param id - ID of the audio file
   * @returns AudioFile | undefined
   */
  public getAudioFile(id: string): AudioFile | undefined {
    return this.audioFiles[id];
  }

  /**
   * Gets the duration of an audio file
   * @param id - ID of the audio file
   * @returns number - Duration in seconds, or 0 if not found
   */
  public getAudioDuration(id: string): number {
    const audioFile = this.audioFiles[id];
    return audioFile ? audioFile.duration : 0;
  }

  /**
   * Synchronizes audio with timeline
   * @param timelineTime - Current time in the timeline
   * @param audioId - ID of the audio file to synchronize
   * @param audioStartTime - Start time of the audio in the timeline
   * @returns AudioSyncInfo - Synchronization information
   */
  public synchronizeAudio(timelineTime: number, audioId: string, audioStartTime: number): AudioSyncInfo {
    const audioFile = this.audioFiles[audioId];
    
    if (!audioFile) {
      return {
        isPlaying: false,
        currentTime: 0,
        volume: 0
      };
    }
    
    const audioElapsedTime = timelineTime - audioStartTime;
    
    // Check if audio should be playing
    const isPlaying = audioElapsedTime >= 0 && audioElapsedTime <= audioFile.duration;
    
    // Calculate current time in the audio file
    const currentTime = isPlaying ? audioElapsedTime : 0;
    
    // Calculate volume (can be adjusted based on distance from start/end)
    let volume = 1.0;
    if (isPlaying) {
      // Fade in/out at start/end
      const fadeInDuration = 0.5;
      const fadeOutDuration = 0.5;
      
      if (audioElapsedTime < fadeInDuration) {
        volume = audioElapsedTime / fadeInDuration;
      } else if (audioElapsedTime > audioFile.duration - fadeOutDuration) {
        volume = (audioFile.duration - audioElapsedTime) / fadeOutDuration;
      }
    } else {
      volume = 0;
    }
    
    return {
      isPlaying,
      currentTime,
      volume
    };
  }

  /**
   * Gets the audio context
   * @returns AudioContext | null
   */
  public getAudioContext(): AudioContext | null {
    return this.audioContext;
  }

  /**
   * Checks if the service is initialized
   * @returns boolean - Initialization status
   */
  public isServiceInitialized(): boolean {
    return this.isInitialized;
  }

  /**
   * 获取音频文件信息
   * @param filePath - 音频文件路径
   * @returns Promise<AudioFileInfo> - 音频文件信息
   */
  private async getAudioFileInfo(filePath: string): Promise<AudioFileInfo> {
    // 在实际实现中，这里会使用专业的音频处理库来获取准确的文件信息
    // 例如使用ffmpeg或其他音频处理工具
    
    try {
      // 使用fluent-ffmpeg获取准确的音频信息
      const ffmpeg = await import('fluent-ffmpeg');
      const fs = await import('fs');
      
      // 设置FFmpeg路径
      const ffmpegPath = process.env.FFMPEG_PATH || 'ffmpeg' ;
      if (fs.existsSync(ffmpegPath)) {
        ffmpeg.setFfmpegPath(ffmpegPath);
      }
      
      // 获取文件大小
      const stats = fs.statSync(filePath);
      
      // 使用ffprobe获取准确的音频元数据
      const metadata = await new Promise<any>((resolve, reject) => {
        ffmpeg.ffprobe(filePath, (err: any, data: any) => {
          if (err) {
            reject(err);
          } else {
            resolve(data);
          }
        });
      });
      
      // 从元数据中提取准确的时长和比特率
      const duration = metadata.format.duration || 0;
      const bitrate = metadata.format.bit_rate || Math.round((stats.size * 8) / duration);
      
      return {
        duration: duration,
        fileSize: stats.size,
        bitrate: bitrate
      };
    } catch (error) {
      // 如果fluent-ffmpeg不可用或出错，回退到基于文件大小的估算
      console.warn('Failed to get accurate audio file info with ffmpeg, falling back to estimation:', error);
      const fs = await import('fs');
      const stats = fs.statSync(filePath);
      
      // 粗略估算时长（基于文件大小和假设的比特率）
      const bitrate = 128000; // 假设128kbps比特率
      const duration = (stats.size * 8) / bitrate; // 时长（秒）
      
      return {
        duration: duration,
        fileSize: stats.size,
        bitrate: bitrate
      };
    }
  }
}

/**
 * AudioFile Interface
 * 
 * Represents an audio file.
 */
interface AudioFile {
  id: string;
  filePath: string;
  duration: number;
  buffer: AudioBuffer | null;
  isLoading: boolean;
}

/**
 * AudioSyncInfo Interface
 * 
 * Represents synchronization information for an audio file.
 */
interface AudioSyncInfo {
  isPlaying: boolean;
  currentTime: number;
  volume: number;
}

/**
 * AudioFileInfo Interface
 * 
 * Represents information about an audio file.
 */
interface AudioFileInfo {
  duration: number;
  fileSize: number;
  bitrate: number;
}
